The present invention relates to an electronic automobile anti-theft apparatus.
A mechanical steering wheel lock is widely used in the prior art to prevent automobile theft. FIG. 1 shows an example of a steering lock 51, which includes a key cylinder 54 and a lock pin 52. A key (not shown) is inserted in the key cylinder 54 and rotated to actuate the lock pin 52 so that the lock pin 52 engages a steering shaft 53. This prohibits the rotation of the steering shaft 53 and a steering wheel (not shown).
Electronic key systems have recently become popular. An electronic key system starts an engine without using a key. Accordingly, there is a demand for an electronic automobile anti-theft apparatus, such as an electronic steering wheel lock that locks a steering wheel with an actuator (e.g., motor).
However, when employing an electronic steering wheel lock, electric noise may cause an electronic control unit (ECU) to actuate a motor, which actuates a lock pin, and lock the steering shaft with the lock pin in an unintentional manner. To solve this problem, a solenoid 103 may be employed, as shown in FIG. 2, to lock the lock pin when the lock pin is disengaged from the steering shaft. The solenoid 103 is connected to an interlock power supply line 105 of an electronic steering wheel lock 101. The supply of power to the solenoid 103 is controlled by a FET 106, which is activated and inactivated in accordance with an activation signal provided from a microcomputer 104. That is, the lock pin is locked when the solenoid 103 is deactivated and unlocked when the solenoid 103 is activated.
The microcomputer 104 may provide the FET 106 and FETs 107a–107d with an unintentional activation signal when electric noise is produced. In such case, a motor 102 may be actuated and the solenoid 103 may be activated thereby unlocking the lock pin. This would engage the lock pin with the steering shaft. Accordingly, the electronic steering wheel lock 101 does not solve the above problem.